Electrode Tab Bulge Prevents Separator Damage
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Solution Overview
Problem
During the manufacturing of nonaqueous electrolyte secondary batteries, the electrode tab at the longitudinal-direction end portion of the winding-start side can damage the separator and electrode, leading to defects like current leakage, and existing methods do not adequately reduce this damage.
Innovation Solution
A method involving the processing of the electrode tab to form a gap between the tab and the winding core, allowing the tab's width-direction central portion to bulge outward, thereby reducing stress on the separator and electrode during the winding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrode tab is bonded to a longitudinal-direction end portion of an electrode at a winding-start side, then the battery capacity increases and internal resistance decreases, but the separator and electrode are damaged at the overlapping portion causing current leakage
Solution Approach 1:
The electrode tab is processed in advance to form a bulge at its width-direction central portion before winding. This preliminary shaping creates a gap between the tab and winding core, preventing the tab edge from overlapping and damaging the separator and electrode during the winding process, while still allowing the tab to be bonded to improve battery performance
Solution Approach 2:
Only the width-direction central portion of the electrode tab is processed to bulge outward, while the edge portions remain relatively flat. This localized processing creates the necessary gap to prevent damage at critical areas (where the tab would overlap the separator) while maintaining the bonding functionality at the electrode connection points
2Reliability
If an electrode tab is provided at a longitudinal-direction end portion of an electrode, then the battery performance improves, but metal powder and active material powder are generated by damage on the electrode
Solution Approach 1:
The electrode tab is pre-processed to form a bulge that creates a gap with the winding core before the winding process begins. This prevents mechanical damage during winding, thereby preventing the generation of metal powder and active material powder that would otherwise occur when the tab edge overlaps and damages the electrode
Solution Approach 2:
The bulge is formed specifically at the width-direction central portion of the tab, which is the area most likely to overlap with the electrode during winding. This localized modification prevents powder generation at the critical overlapping region while maintaining the structural integrity and electrical functionality of the tab
Data Source
AI summary
A method for manufacturing a nonaqueous electrolyte secondary battery, when an electrode tab is provided at a longitudinal-direction end portion of an electrode located at a winding-start side of an electrode body, the method being capable of sufficiently reducing damage on a separator and the electrode in a process for manufacturing the electrode body. In a manufacturing step of one example of an embodiment, a negative electrode tab is bonded to a longitudinal-direction end portion of a negative electrode to be located at a winding-start side of an electrode body, the negative electrode tab is processed so that a width-direction central portion of the negative electrode tab at least bulges toward a winding-outer side of the electrode body, and while a gap is formed between the negative electrode tab and a winding core, a positive electrode, the negative electrode, and a separator are wound around the winding core.